[Sync] Replace typedef with using.

components/sync/base/immutable_unittest.cc

Index: components/sync/base/immutable_unittest.cc
diff --git a/components/sync/base/immutable_unittest.cc b/components/sync/base/immutable_unittest.cc
index c59d9bcb4667e3596465b1845609cd2e2e8b1f8d..6c8d2a89674ba008d277cb2aba41b0271a1c1001 100644
--- a/components/sync/base/immutable_unittest.cc
+++ b/components/sync/base/immutable_unittest.cc
@@ -87,9 +87,9 @@ class TokenBase {
   scoped_refptr<TokenCore> core_;
 };
 
-typedef TokenBase<USE_DEFAULT_SWAP> Token;
-typedef TokenBase<USE_FAST_SWAP_VIA_ADL> ADLToken;
-typedef TokenBase<USE_FAST_SWAP_VIA_SPECIALIZATION> SpecializationToken;
+using Token = TokenBase<USE_DEFAULT_SWAP>;
+using ADLToken = TokenBase<USE_FAST_SWAP_VIA_ADL>;
+using SpecializationToken = TokenBase<USE_FAST_SWAP_VIA_SPECIALIZATION>;
 
 void swap(ADLToken& t1, ADLToken& t2) {
   t1.Swap(&t2);